APPLICATION OF HYDROGEN STORAGE ALLOY TO REMOVE PROTECTING GROUPS

Hydrogen storage alloys are capable of charging and discharging hydrog en in temperature-dependent manner, and are employed as catalysts for hydrogenation and dehydration. In water, CaNi5 removed protecting grou ps such as benzyloxycarbonyl, benzyl ester, benzyl ether and nitro gro ups without any side reactions, and the reaction time was highly depen dent on the hydrogen pressure of the reaction system. In organic solve nts such as dioxane and EtOAc the deprotection reaction did not procee d. Methanol (MeOH) was applicable, but the reaction in MeOH required a longer reaction time than in water. A mixture of water and MeOH accel erated the reaction depending on the mater content. Although the mecha nism of the catalytic hydrogenation with CaNi, in water and/or MeOH is uncertain, the reaction between Ca and water or MeOH seems to be of c ritical importance.